1. Field of the Invention
The present invention relates to a multi-conductor lead assembly comprising a first lead, a second lead and a connector assembly for connecting the proximal end portion of the first lead to the distal end portion of the second lead. More specifically, the invention relates to the connector assembly which provides a simple and effective structure for connecting a conductor in the second lead to one of several sleeve electrodes on the proximal end of the first lead in a sealed manner whereby the connector assembly can be inserted in body tissue after the distal end of the first lead with ring electrodes thereon has been implanted in body tissue, electrical tests first have been made, by means of electrical connections to the sleeve electrodes on the proximal end of the first sleeve, on the sensitivity of the implanted ring electrodes and a connection is made from a selected ring electrode on the distal end of the first lead to the conductor in the second lead.
2. Description of the Prior Art
Heretofore, it has been desirable, in the field of multi-electrode leads which are inserted into the epidural space within the spine and adjacent the spinal cord, to be able to determine which of a number, such as, for example, four, electrodes implanted in the spine are in good conductive contact with the spinal cord. In this respect, it is desirable to be able to test and determine which of the distal electrodes has the best conductive contact with the spinal cord.
One technique which has been proposed for achieving this result is to provide a cathode electrode assembly having four equally spaced in line electrodes along the exterior of a sheath at the distal end of the catheter which are connected to proximal terminals at the proximal end by individually insulated strands of steel wire conductor.
A wire is connected to and extends from each of the proximal terminals to an external terminal each of which is adapted to extend out of body tissue for cutaneous testing during a trial period of stimulation. The wires are cut adjacent the proximal terminals and removed prior to permanent implantation of the multi-conductor lead assembly and before the proximal terminals at the proximal end of the catheter are connected to an implanted stimulator.
Such an assembly is disclosed in the Borkan et al U.S. Pat. No. 4,379,462.
As will be described in greater detail hereinafter, the multi-conductor lead assembly of the present invention, instead of having external terminals which are cut away from a lead, includes two leads, a first lead which has distal electrodes adapted to be implanted within a spine, a second lead with having a wire conductor therein and a proximal terminal assembly including a terminal pin adapted to be inserted into a neural stimulator, and a connector assembly at the distal end of the second lead into which the proximal end of the first lead is adapted to be inserted after testing is performed, such as with alligator clips connected to sleeve electrodes on the proximal end portion of the first lead when it is withdrawn from the tissue for testing purposes. After the testing, the proximal end of the first lead is inserted into the connector assembly and a clip connector at the distal end of an insulated wire conductor connected to the wire conductor in the second lead is connected to a selected one of the sleeve electrodes on the proximal end of the first lead. Then the connector assembly is sealed and implanted in body tissue and the proximal end of the wire conductor in the second lead is connected to an implanted or external neural stimulator.